The evolutionary idea of development greatly influenced the develop­ment of anatomy. A metaphysical view of nature reigned in biology until the second half of the nineteenth century. The Swedish naturalist Carolus Lin­naeus (Karl von Linne, 1707-1778), in his work Systema Naturae, proposed a "ladder of living beings" on which he arranged all animals according to species and order, placing man at the top. The creation of this zoological ladder was the most valuable achievement of eighteenth-century natural science because it offered the first classification of the animal world, which is used to this day. This classification, however, included the concept of the immutability of the animal species and of the origin of man as the result of "divine creation". In opposition to this metaphysical view, the dialectical theory of devel­opment began gaining strength in the nineteenth century. It caused a revolu­tion in biology and medicine and formed the basis of Darwinian theory, which in turn served as the foundation for evolutionary morphology. The previous course of science, particularly of embryology and compara­tive anatomy, paved the way for Darwinism. A member of the Russian Aca­demy of Sciences, C. F. Wolff (1733-1749), for instance, showed that organs are not preformed during embryogenesis (preformism), but originate and devel­op anew (epigenesis). In opposition to the idealistic theory of preformism and to the biblical interpretation of the origin of the embryo, Wolff therefore ad­vanced the materialistic theory of epigenesis and pioneered the study of materialistic embryology, for which he was persecuted by adherents of idealism. The French naturalist Jean Baptiste Lamarck (1744-1829) was among the first to propound, in his work Philosophie Zoologique (1809), the idea of the organism's evolution under the influence of the environment. The Soviet biologist Michurin and his followers later freed Lamarckism from idealism while preserving its rational core (the possibility of the inheritance of ac­quired characters) in their work. The Russian Academician K. M. Baer (1792-1876), in continuing Wolff's embryological research, discovered the ova of mammals, including man, and determined the principal laws governing the individual development of organisms (ontogenesis), which underlie modern embryology. Known as the Father of Embryology, Baer investigated the early stage of embryonal devel­opment (the blastula) and developed the theory of germinal layers. He advanced the idea of the transformation of species before Darwin, and, al­though he later criticized Darwin's theory of the struggle for existence, he nonetheless claimed to have "paved the way for Darwin's theory". Engels appraised the activity of all the scientists mentioned above as follows: "... C. F. Wolff in 1759 launched the first attack on the fixity of spe­cies and proclaimed the theory of descent. But what in his case was still only a brilliant anticipation took firm shape in the hands of Oken, Lamarck, Baer, and was victoriously carried through by Darwin in 1859, exactly a hundred years later."1 The brilliant English scientist Charles Darwin (1809-1882), in his epoch-making work The Origin of Species (1859), proved that animal species change in the process of adaptation to the conditions of existence. He also established the unity of the animal kingdom and man's place in its evolutionary process. Darwin came to the conclusion that man, like the modern anthropomorphic monkey, descended from highly developed, anthropoid apes resembling man though now extinct. Darwinism, the complex of facts and theory developed by Darwin, dealt religion a crushing blow by challenging the biblical legend claiming that man was created by God. For this reason, the church and reactionary science hindered the development of Darwinism in Western Europe and America. In Russia the work of progressive Russian scientists-materialists (the brothers A. 0. and V. 0. Kovalevsky, I. M. Setschenow (Sechenov), E. I. Metchnikoff, K. A. Timiryazev, A. N. Severtsov, and others) aided the rapid development of Darwinism. E. I. Metchnikoff (1845-1916) established that, in the period of embryon­al development, both invertebrates (with the exception of coelenterates) and chordates have three germinal layers. This discovery established the first link between the invertebrates and the vertebrates. The second link was A. 0. Kovalevsky's (1840-1901) discovery in the adult Balanoglossus of certain features inherent in the chordates (gill slits, germs of the chorda). Finally, A. 0. Kovalevsky succeeded in proving that the lancelet was a hybrid form since it had features of both invertebrates (e.g. the skin structure) and verte­brates (e.g. the presence of an axial skeleton, i.e. the chorda, and the location of the nervous system). From his study of the development of the Balanoglos­sus, Ascidia, lanceletes and vertebrates, Kovalevsky was able to reform the classification of the animal kingdom and establish a new phylum, Chordata, to which man also belongs. By establishing a connection between the invertebrates and the verte­brates, Kovalevsky filled the gap existing at the time in Darwin's doctrine. Darwin himself appraised this discovery highly. Kovalevsky also determined that the nervous system arose from the outer germ layer (ectoderm) while the primary gut arose from the internal layer (entoderm). The embryological research carried out by Kovalevsky, as well as by Baer, Mueller, Darwin, Haeckel, was reflected in the biogenetic law "onto­genesis repeats phylogenesis". This law was formulated more thoroughly and corrected by A. N. Severtsov, who showed the influence of environmental fac­tors on animal body structure. By applying evolutionary science to the study of anatomy, Severtsov became the founder of evolutionary morphology. In this way Darwinism developed in the works of Russian morphologists and embryologists. The classics of Marxism-Leninism criticized Darwin's theory for certain methodological errors, but nonetheless appraised it highly as one of the three greatest discoveries in natural science of the nineteenth century. Darwin's solution to the problem of evolution—man's descent from ape-like ancestors—was necessarily one-sided since he dealt with the problem only from the biological perspective. This one-sided approach prevented him from discussing the factors which determined man's origin. This problem was solved by the founders of Marxism, Karl Marx and Friedrich Engels. Engels in his work The Part Played by Labour in the Transition from Ape to Man (written in 1876, published in 1896) showed that the use of tools was the decisive factor in the formation of man. His hypothesis, expressed in the phrase "labour created man", states that the use of tools transformed a tribe of apes into a human society. Engels' theory, called the labour theory of the origin of man, formed the basis of progressive modern science. Darwin's theory and Engels' labour theory greatly influenced the study of human anatomy and posed a number of new questions to anatomists whose task was now not only to describe and explain the human body structure, but to disclose the regular patterns of its formation so that further changes to the human organism might be directed. These questions particularly con­cerned Soviet anatomists, working in the best traditions of their native school of anatomy, a short account of which follows.